In recent years, across the globe, several incidents of failures of mechanical components are observed in the power generation sector, nuclear industry, chemical industry, and process industry due to surface cracking. To meet such challenges, cladding of superalloys on the substrate can be done by using advanced welding processes. Although cladding improves mechanical properties, through service life delamination of the weld cladding from the substrate results in collateral damage to components as a turbine and valve failure, mainly due to complex metallurgical changes by uneven cooling and heating in the heat affected zone (HAZ) of the substrate during cladding. The HAZ can vary in severity and size depending on the composition of cladding material and substrate, heat intensity, and the cladding process. It leads to drastic changes in mechanical properties such as creep and fatigue resistance, distortion, and surface cracking. This makes it extremely crucial to learn about the microstructure characterisation of HAZ during cladding. This article provides information related to metallurgical reaction in the HAZ during the deposition of superalloy on substrate. The article aims to address major issues related to HAZ as variation of hardness profile and type of HAZ cracks. Furthermore, an intense review on the controlling approach of HAZ formation is included. Also highlighted are overall findings related to HAZ formation and its influence on metallurgical and mechanical properties, and possible future direction in the context of critical challenges that need to be catered prior to cladding. After performing a comprehensive study on HAZ formation during the cladding operation, it is observed that HAZ formation is a complex phenomenon, it is affected by various factors viz. heat input, cladding processes, properties of materials, etc. Efforts have been made to summarise all the information related to HAZ.
Cylindrical pressure vessels are integral structural components in modern spacecraft. They are used to hold propellants, coolant fluids, and life-support gases at high pressure in spacecrafts. Fracture analysis of these cylindrical pressure vessels is essential for assuring their structural durability under the effects of internal pressure and temperature. During orbital operations, these vessels are exposed to rapid temperature fluctuations caused by solar radiation and deep-space cooling, which generate substantial thermomechanical stresses. This study investigates the fracture behaviour of cylindrical pressure vessels subjected to combined pressure and thermal loading to support the development of more resilient spacecraft structures. The elastic-plastic stresses in a thick-walled cylinder composed of functionally graded isotropic material subjected to internal pressure and external temperature is obtained by using analytical method. By applying the boundary conditions, the governing differential equation is solved to determine the stresses. Based on graphs and mathematical computations, it is observed that if the value of temperature increases, stresses on inner surface increase, whereas decrease on the outer surface of the cylindrical pressure vessel. Also, stresses increase on the inner surface when pressure increases. Therefore, it can be concluded that thick-walled cylindrical pressure vessel of FGM (aluminium) is more suitable in direct sunlight (for extremely high temperatures), and the cylindrical pressure vessel of FGM (stainless steel) is more suitable under shadow (for extremely low temperatures) for crew and life support systems in spacecraft design.
Aluminium based hybrid metal matrix composites (HMMCs) are extensively utilised in modern engineering applications due to their strength-to-weight ratios. This study presents a multi-criteria decision making (MCDM) approach to optimise the processing parameters. In this study, we have considered parameters of fabricated aluminium 6061-based hybrid metal matrix composites reinforced with silicon carbide (SiC) and molybdenum disulfide (MoS2) using the stir-casting technique. The mechanical performance of the developed composites is evaluated by considering key parameters such as hardness and ultimate tensile strength (UTS), providing insight into the structural integrity and load-bearing capacity. In this study, eight alternative materials A1-A8 consisting of Al 6061/SiC/MoS2 with different reinforcement variations are considered as candidate materials, and MC DM methods are applied to determine the optimal composite. The Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) and VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) decision methods are employed to rank the alternatives for the composite formulations. The entropy weight method is applied to determine objective criterion weights. The obtained weights are incorporated into the TOPSIS and VIKOR methods to rank the alternative based on the closeness coefficient. The alternative A6 (88 wt.% Al, 10 wt.% SiC, and 2 wt.% MoS2) as the optimal formulation, exhibiting a maximal hardness of 208 HV and an ultimate tensile strength (UTS) of 194 MPa, indicating superior mechanical performance. The evaluation results indicate that alternative A6 achieves the best performance among all candidates, obtaining a TOPSIS closeness coefficient of 1.00 and a VIKOR index of 0.00, whereas alternative A3 shows the lowest performance with a TOPSIS score of 0.00 and a VIKOR value of 1.00, confirming the consistency of both decision-making approaches. The developed approach provides a systematic and reliable tool for material selection and can assist researchers in optimising aluminium based hybrid composites for advanced engineering and tribological applications.
This study presents a structural integrity assessment framework for flexible pavement systems using multi-temporal Interferometric Synthetic Aperture Radar (InSAR) deformation analysis. Sentinel-1 time-series data are processed using Small Baseline Subset (SBAS) and Persistent Scatterer Interferometry (PSI) techniques to quantify settlement trends along a highway corridor. Surface deformation rates are interpreted in terms of subgrade compressive strain, tensile strain at the bottom of the bituminous layer, fatigue life reduction, and rutting susceptibility. Maximum settlement rates of 20-22 mm/year are identified in embankment and culvert transition zones. A mechanistic interpretation framework is introduced to relate observed deformation trends to fatigue life Nf and serviceability limit states. Validation using GNSS and levelling data yields RMSE values between 6-12 mm. Results demonstrate that InSAR-derived deformation indicators provide a reliable proxy for network-level structural integrity and durability assessment of flexible pavement systems.
This research analyses heat and mass transfer phenomena in Williamson non-Newtonian fluid over a porous stretching surface with suction and internal heat source effects. Dominant factors encompass mixed convection, nonlinear radiative heat flux, magnetic Lorentz drag from a tilted field, reactive species interactions, and buoyancy forces, alongside variable viscosity, viscous dissipation, and surface velocity slip. Momentum, thermal energy, and mass diffusion equations are formulated and transformed via similarity variables into a set of nonlinear ODEs. Numerical solutions are obtained using the bvp4c function in MATLAB®. Distributions of speed, thermal, and species solute are illustrated graphically to reveal parameter impacts. Key amounts of engineering interest skin friction coefficient. Heat and mass transfer rates are computed and tabulated. Model validation confirms close alignment with published benchmarks. Notably, MHD, radiation, and buoyancy synergistically enhance thermal and solute transport rates.
